COVID-19 Vaccines for Children Under 5: UCSF Explains What You Should Know

By Jeffrey Norris

An infant receives her first COVID-19 vaccine from a UCSF nurse while her mom and dad hold her
Mae Purdy, almost a year old, receives her first COVID-19 vaccine at UCSF Medical Center with support from her mom Britt, left, and her dad Jon Purdy. Photo by Susan Merrell

Parents of children under the age of five-years-old now have the option to vaccinate their infants and young children against COVID-19.

The Food and Drug Administration granted emergency authorization for Pfizer-BioNTech and Moderna m-RNA-based COVID-19 vaccines for young children in June, nearly 18 months after vaccines were first approved for adults. Following the FDA’s authorization, the Centers for Disease Control and Prevention accepted CDC advisory committee recommendations for vaccination of infants and other children. 

The Moderna vaccination protocol calls for two vaccinations, each one-quarter of Moderna’s adult vaccine dose, spaced four weeks apart. An earlier Pfizer-BioNTech protocol also included two vaccinations, each one-tenth of the adult dose and spaced three weeks apart, but this failed to meet FDA criteria for authorization and was withdrawn from consideration. Pfizer added a third dose, administered eight weeks after the second, and collected additional data for FDA submission before the three-dose protocol was authorized.

The latest FDA approvals were granted primarily based on antibody immune responses generated by the vaccines. The vaccines mustered responses comparable to those measured in earlier COVID-19 vaccine trials of adults – despite the lower dosages. There were not a statistically large number of infections or serious outcomes in the trails, but it appears the new COVID vaccination protocols might be roughly as effective as a typical flu vaccine in preventing infection. 

We spoke to Lee Atkinson-McEvoy, MD, a professor of pediatrics at UC San Francisco, for more on what parents should know about COVID-19 vaccines for young children.

Vaccination Side Effects

What do you tell parents to be aware of when it comes to COVID-19 vaccination side effects?

Vaccines trigger the immune system, and many side effects are similar to being ill. So, after this vaccine we see things like fever, fatigue, and aches, similar to being sick. Side effects are short-lived, usually lasting just a day or two. The dose of vaccine was adjusted to make the likelihood of side effects less for infants and young children.

What vaccine reactions should prompt a visit to the doctor’s office?

Call your child’s physician’s office if you have any concerns that worry you after the vaccine. You should be seen if side effects last longer than one-to-two days, if fever is greater than 104ºF (39.5º C), if your child is not acting well, or for other serious concerns.

Risks of COVID-19 in Children

Only a minority of children ages 5 to 11 have been fully vaccinated since they became eligible last November. What do you say to hesitant or reluctant parents?

It’s true that COVID in children is often milder and less likely to lead to serious outcomes. However, there have been deaths in children due to COVID, and some children experience severe COVID, including Multisystem Inflammatory Syndrome in Children (MIS-C), a serious condition in which organs become inflamed. Many of those children did not have any underlying health conditions before they became sick with COVID. Vaccination decreases these risks.  

With the emergence of Omicron and its subvariants, hospitalization rates among the population of children ages four and under has overtaken rates seen in older children. More than half of young children hospitalized for COVID in this age group have had no pre-existing medical conditions. What symptoms should parents view as warning signs of potentially serious illness, and when should they consult their child’s physician’s office?

If their child has a high fever greater than 104º F (39.5º C), appears sick, or is urinating less than three times per day, or if parents have other concerns, they should contact their child’s physician’s office.

Vaccination Access 

Are parents receiving adequate information on childhood COVID-19 vaccination, and sufficient access to COVID vaccines?

It’s important to consider that many parents may struggle with transportation or with work obligations that make daytime scheduling or consulting with physicians difficult. At UCSF, we are doing outreach to ensure there is access to accurate and expert information to address concerns and questions, and access to vaccine clinics at times that work for families.

Infants and the youngest children now are eligible for COVID-19 vaccination and simultaneously for routine childhood vaccinations for other diseases. Is it safe for children to receive COVID-19 and other vaccines during the same clinic visit?

Yes, children can receive other routine and recommended vaccinations at the same time as a COVID vaccination.

So far, we still see low rates of COVID vaccination among eligible children, but how are routine vaccination rates now?

We have seen that some children are falling behind with childhood vaccinations because COVID prevented them from coming in for routine appointments. COVID vaccination decreases risk for serious COVID illness, and by preventing COVID in the family, allows children to be well enough to attend routine appointments for important screenings and vaccinations against other major illnesses.

Vaccination Effectiveness

Considering the different protocols, as well as the clinical trial results presented to the CDC advisory committee, are you equally enthusiastic about both new vaccines?

Both vaccines provide great protection against severe COVID and some protection from getting milder COVID. The Pfizer is a three-dose series over 11 weeks, and the Moderna is a two-dose series over four weeks. We know that since vaccines have been available, the protection of any one brand of vaccine against COVID-19 changed based on the predominant variant around. The vaccine studies have been focused on safety of the vaccine and have been studied across a diverse population of children. The bottom line is vaccination is better than no vaccination.